Bridge plate lifting device

ABSTRACT

Apparatus for counterbalancing a bridge plate hinged to a supporting structure, such as the end of a railroad flat car. The lifting force is provided by a helical spring positioned in a tubular housing mounted in fixed position on the supporting structure. One end of the helical spring is anchored to the housing and the opposite end of the helical spring is anchored to a shaft journaled in the housing. The lifting arm which engages the bridge plate is adjustably secured on one end of the shaft in such a manner that the spring may be wound to the desired tension before mounting the lifting arm on the shaft by simply turning the shaft with a wrench or the like.

United States Patent 3,063,386 11/1962 Price [72] Inventor Robert M. Akers 3,216,373 11/1965 Boone 105/458 1301 E. Reno, Oklahoma City, Okla. 3,327,650 6/1967 Bridges et a1. 105/458 [21] Appl. No. 800,686 3,334,368 8/1967 McIntosh et a1. 14/71 [22] Filed Feb. 19, 1969 3,460,175 8/1969 Beckwith et a1. 14/71 {45] Patented Jan. 19, 1971 Continuation-impart of application Ser. No. 52 g l g f :i 694,147, Dec. 28, 1967, now abandoned. "'"9 un aney es m [54] ggff g g DEVICE ABSTRACT: Apparatus for counterbalancing a bridge plate hinged to a supporting structure, such as the end of a railroad U.S. flat can The force is provided a pring posi- 14/71 tioned in a tubular housing mounted in fixed position on the llll. supporting structure one end of the helical pring is anchored 501d 15/00 to the housing and the opposite end of the helical spring is of Search anchored to a shaft journaled in the housing The arm 458; 14/71 which engages the bridge plate is adjustably secured on one 56 R f C" d end of the shaft in such a manner that the spring may be 1 e erences e wound to the desired tension before mounting the lifting arm UNITED STATES PATENTS on the shaft by simply turning the shaft with a wrench or the like.

Pmmmmwm 3555020 SHEET 1 0F 2 INVENTOR.

' plication of the This is a continuation-impart of applicant's copending aps'ame title, Ser. No. 694,l47, filed Dec. 28.

BACKGROUND OF THE INVENTION As it is well known in theart, the use of railroad flat cars for hauling trucks and trailers has become popular in recent years. In such operations it is frequently'desirable to move a truck or trailer from one flat car to another. and for this purpose, abridge plate is normally hinged to one end of one flat car and a similar bridge plate is hinged to the adjacent end of an adjacent flat car. Each bridge plate can be swung downwardly to bridge the space between the adjacent flat cars,.and the bridge plates. are spaced apart transversely a distance such that a truck or trailer may be moved thereacross from one flat car to the other. In all cases the bridge plates are so heavy. usually weighing several hundred pounds, as to require two or more men forraising and lowering the bridge plates. It should be further noted that the bridge plates vary appreciably in weight from one installation to another.

The bridge plate lifting device disclosed in applicant's above-mentioned copehding application has been found to be highly useful. However. adjustment of the liftingfforce when the device is installed or used on a different weight of bridge plate has been found to be more time consuming than is desirable.

SUMMARY OF THE INVENTION The present invention contemplates an apparatus for counterbalancing a bridgeyplate hinged to a supporting structure for swinging movement between a substantially vertical position and a substantially horizontal position which includes an elongated housing and means for securing the housing to the supporting structure on the side of the bridge plate toward which the bridge plate swings in moving toward a horizontal position. An elongated shaft is journaled in the housing substantially parallel with the swinging axis of the bridge plate and at least one end of the shaft protrudes from the housing. A mounting means secures the lifting arm on the protruding end of the shaft with the arm extending substantially radially from the shaft at any one of a plurality of circumferential positions with respect to the shaft. A helical spring is telescoped around the shaft withinthe-housing and has one end thereof secured to the shaft while the other end thereof is anchored to the housing. Means are provided for turning the shaft and winding the spring when the arm is not attached to the shaft, whereby the spring may beplaced under the desired torsional tension, and then the arm issecured to the shaft-to adjust the counterbalancing. force'exerted by the lifting arm on the bridge plate. The spring will remain woundby virtue of the contact of the lifting arm with the bridge plate.

. An'object of the invention is to decrease the effort required inraising and lowering bridge plates, and particularly bridge plates employed on railroad flat cars.

Another object ofthe inventionis to provide anapparatus for counterbalancing a-bridge plate which may be .easily and quickly adjusted to provide the desired lifting or counterbalancing force.

Afurther object of this invention is to provide an apparatus for counterbalancingabridge plate which may be employed forcounterbalancing a wide range of bridge plates of different weights.

A still further object of this invention is to provide an apparatus for counterbalancing abridge platewhich is economical in construction and will havea long service life.

Other objects and advantages of the invention will be evident from thefollowingdetailed description when read in conjunction with the accompanying drawing which illustrates the invention.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic side view of adjacent end portions of railroad flat'cars illustrating a use of the present invention.

FIG. 2 is a schematic end view of a railroad flat car showing the installation of an embodiment of this invention.

FIG. 3 is a combined'cross-sectional and elevational view of the apparatus.

FIG. 4 is an end view of the apparatus.

FIG. 5 is a partial view of the opposite end of the apparatus as indicated by the lines 5-5 on FIG. 3.

FIG. 6 is a sectional view taken along lines 6-6 of FIG. 3.

FIG. 7 is another sectional view taken along lines 7-7 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in detail, and particularly FIGS. 1 and 2, reference character 10 generally designates the apparatus of this invention which, in a typical environment, will be installed on one end of a railroad flat car 12 adjacent one side 14 thereof. The apparatus 10 includes a lifting arm 16 which slidably engages a bridge plate 18 through the medium of a shoe 20. The bridge plate 18 is hinged to the flat car 12 by a hinge pin 22 and is of a size to be moved from a substantially vertical position as shown in full lines in FIG. 1 to a substantially horizontal position as shown in dashed lines in FIG. I to bridgethe space between the flat car 12 and an adjacent flat car.24. It may also be noted at this point that a bolt 26 is normally extended through a bracket 28 on one side of the bridge plate 18 and a bracket 30 fixed to the flat car 12 to hold the bridge plate 18 in a substantially vertical position. The bridge plate 18 is released for swinging down to a horizontal position by simply raising the locking bolt 26 upwardly out of the bracket 30.

The apparatus 10 is illustrated in detail in FIGS. 3 through 7. As shown in FIG. 3,.the apparatus 10 comprises a tubular. elongated housing 32 having a plurality of suitable mounting brackets or feet 34 thereon for rigidly securing the housing to the respective end of the flat car or other supporting structure on whichthe apparatus is to be used. An end cover plate 36 is welded or otherwise rigidly secured on each end of the housing 32 and each plate 36 has an aperture 38 in the central portion thereof receivinga bearing 40. A shaft 42 is journaled in the bearings and protrudes from the opposite ends of the housing 32.

It will be noted that each bearing 40 has a circumferential flange 44 on the inner end thereof which is positioned between a shoulder 46 on the shaft 42 and an inturned portion 48 of the respective cover plate 36, whereby the bearings 40 and the shaft 42 will be secured in the desired endwise positions upon assembly of the apparatus as illustrated in FIG. 3. A circular plate 50 is preferably secured to the outer face of each cover plate 36 and is shaped to retain a sealing washer 52 around the adjacent portion of the shaft 42 and against the outer end of the respective bearing 40 reform a seal for lubricant which is normally provided in the housing 32 for the bearings 40. v

A helical spring 54, having an inner diameter larger than the diameter of the shaft 42, is telescopically positioned in the housing 32 around the shaft 42. One end 56 of the spring 54 is positioned in a slot 58 formed in a circumferential flange 60 formed around the shaft 42 adjacent one end of the housing 32 for effectively anchoring the end 56 of the spring 54 to the shaft 42. The opposite end 62 of the spring 54 is positioned in a slot 64 of a drive plate 66. The drive plate 66 is welded or otherwise rigidly secured in the housing 32 and has an enlarged aperture 68 in the central portion thereof to prevent the drive plate from engaging the shaft 42. Thus, the end 62 of the spring 54 is effectively anchored to the housing 32.

it may also be observed in FIGS. 3 and 6 that a plurality of guides 70 in the form of circumferentially spaced blocks are secured or formed on the shaft 42 adjacent the flange 60 and the drive plate 66. The guides 70 are provided to facilitate the centering of the spring 54 around the shaft 42 when the apparatus is being assembled to help guide the end 56 of the spring 54 into the slot 58 and the end 62 of the spring into the slot 64.

One end 72 of the shaft 42 is provided with wrench flats 74 (FIG. by means of which the spring 54 may be wound or placed under torsional tension. as will be described more in detail below. The opposite end portion 76 of the shaft 42 (FIG. 3) is provided with a plurality of splines 78 spaced around the circumference thereof. A circumferential shoulder 80 is formed on the shaft 42 at the ends of the splines 78 adjacent the housing 32, and the splines 78 are tapered inwardly toward the outer end 76 of the shaft. A threaded portion 82 of reduced diameter is provided on the shaft 42 outwardly of the splines 78.

A mounting block 84 has a bore 86 therethrough in which are formed splines 88 shaped to mate with the splines 78 on the shaft 42, whereby the mounting block 84 may be secured on the shaft 42 in a variety of different circumferential positions. A second bore 90 (FIG. 7) is formed through the mounting block 84 at right angles to the bore 86 to slidingly receive the arm 16. As shown clearly in FIG. 7, the arm 16 and the bore 90 are of rectangular cross section. A pair of setscrews 92 are threaded into the mounting block 84 to engage a side of the arm 16 and rigidly secure the arm 16 to the mounting block 84. The mounting block 84 is in turn held in the desired position on the shaft 42 by means of a washer 94 and a nut 96 threaded onto the threaded portion 82 of the shaft 42.

The arm 16. as shown in both FIGS. 1 and 4, is preferably bent slightly toward the bridge plate 18 when the apparatus is in operating position. The outer end portion 98 (FIG. 3) of the arm 16 is bent at right angles to support the shoe in the proper position for sliding lengthwise along the bridge plate 18 as the bridge plate 18 is raised and lowered. The shoe 20 is preferably in the form of a plate with the opposite ends 100 thereof curved outwardly with respect to the bridge plate 18 to facilitate the sliding movement of the shoe on the bridge plate. A pair of cars or brackets 102 are rigidly secured on the shoe 20 and are apertured to receive a circular portion 104 formed on the extreme outer end of the arm 16. The brackets 102 are journaled on the section 104 of the arm 16, and the shoe 20 is held in position on the section 104 by a locking pin 106 extending through a mating aperture in the extreme end of the arm 16.

OPERATION The apparatus 10 is installed on the end of the flat car 12 by bolting or otherwise rigidly attaching the housing supports 34 to the end of the flat car to position the shaft 42 substantially parallel with the hinge pin or bolt 22 of the bridge plate 18. it will also be noted that the apparatus 10 is installed on the side of the bridge plate 18 which forms the bottom of the bridge plate when the bridge plate is swung downwardly to a substantially horizontal position.

Prior to the assembly of the arm 16 and mounting block 84 onto the shaft 42, the shaft 42 is turned by placing a wrench on the wrench flats 74 to wind or place the spring 54 under tension. The shaft 42 is turned clockwise as viewed in FIG. 4 until the operator estimates that the desired amount of tension is placed in the spring. During this operation, it will be noted that the end 62 of the spring 54 will be held in a fixed position by the drive plate 66, and the turning movement of the turning shaft 42 is transmitted through the flange 60 to the end 56 of the spring 54.

The mounting block 84 is placed over the splines 78 of the shaft 42 with the shoe 20 in contact with the bridge plate 18 while the spring 54 is held under tension, and preferably with the bridge plate 18 held in a substantially vertical position by the bolt 26. The operator then removes the wrench from the flats 74. and the bridge plate 18 may be moved downwardly by the operator to test the amount of counterbalance provided by the apparatus 10. If sufficient tension has not been placed in the spring 54, the mounting block 84 is removed from the splines 78 and the operation repeated. When the desired counterbalancing force is provided, the mounting block 84 is secured in position by the nut 96 and washer 94. The bridge plate 18 is then in condition for a normal operation.

As will be apparent, a wide range of counterbalancing forces may be provided by tensioning the spring 54. Also. the effective length of the arm 16 may be varied by adjusting the position of the arm 16 in the mounting block 84. With this arrangement, the apparatus 10 may be adapted to be used on a variety of sizes and weights of bridge plates. With the apparatus 10, a bridge plate of any size and weight may be operated by a single person using a minimum of effort. it should be further noted that the spring 54 will provide a gradually increasing counterbalancing force on the bridge plate 18 as the bridge plate is moved toward a horizontal position to provide the greatest lift where it is needed. It should further be apparent that the present apparatus is simple in construction, may be economically manufactured and will have a long service life.

Changes may be made in the combination and arrangement of parts or elements as heretofore set forth in the specification and shown in the drawing without departing from the spirit and scope of the invention.

lclaim:

1. Apparatus for counterbalancing a bridge plate hinged to a supporting structure for swinging movement between a substantially vertical position and a substantially horizontal position, comprising:

an elongated housing;

means securing the housing to the supporting structure on the side of the bridge plate toward which the bridge plate swings in moving toward a horizontal position;

an elongated shaft journaled in the housing substantially parallel with the swinging axis of the bridge plate and protruding from at least one end of the housing;

an arm having one end thereof adapted to movably engage the bridge plate;

mounting means for securing the arm on the shaft with the arm extending substantially radially from the shaft at any one of a plurality of different circumferential positions with respect to a shaft;

a helical spring telescoped around the shaft in the housing having one end thereof secured to the shaft and the other end thereof anchored to the housing for urging the arm toward the bridge plate when wound in torsional tension; and

means for turning the shaft and winding the spring, whereby the spring may be placed under a selected torsional tension and then the arm secured to the shaft with said one end thereof in contact with the bridge plate to adjust the counterbalancing force exerted on the bridge plate by the arm.

2. Apparatus as defined in claim 1 wherein said means for turning the shaft and winding the spring includes wrench flats on the shaft positioned exteriorly of the housing.

3. Apparatus as deflned in claim 2 wherein the shaft protrudes from both ends of the housing, the mounting means is secured on one end of the shaft, and said flats are on the opposite end of the shaft.

4. Apparatus as defined in claim 3 wherein the opposite ends of the housing have end cover plates secured thereon apertured to receive the shaft, and characterized further to include a lubricant seal on each end cover plate around the shaft to prevent leakage of lubricant from the housing.

5. Apparatus as defined in claim 1 wherein the shaft has a circumferential flange thereon within and adjacent one end of the housing, a slot in the flange for anchoring the respective end of the spring therein, and characterized further to include a drive plate secured in the opposite end portion of the housing around and out of engagement with the shaft having a slot therein for receiving and anchoring the opposite end of the spring.

6. Apparatus as defined in claim 5 wherein the inner diameter of the spring is larger than the outer diameter of the shaft, and characterized further to include circumferentially spaced guides on the shaft adjacent the flange and the drive plate for facilitating the centering of the spring around the shaft during assembly of the apparatus.

7. Apparatus as defined in claim 1 wherein an end portion of the shaft protruding from the housing has a plurality of circumferentially spaced splines thereon and the mounting means has a bore therethrough and a plurality of circumferentially spaced mating splines in the bore, whereby the mounting means may be secured on the shaft at a plurality of different circumferential positions with respect to the shaft.

8. Apparatus as defined in claim 7 wherein that portion of the arm associated with the mounting means has a polygonal cross section, the mounting means has a mating bore therethrough extending at a right angle to the first mentioned bore slidingly receiving the arm, and setscrews in the mounting means positioned to engage the arm, whereby the effective length of the arm may be adjusted.

9. Apparatus as defined in claim 7 wherein the splines on the shaft are tapered inwardly toward the respective end of the shaft, the splines in the mounting means are similarly tapered, and the end of the shaft adjacent the shaft splines is threaded to receive a nut for wedging the mounting means on the shaft.

10. Apparatus as defined in claim 1 characterized further to include a shoe adapted to slidingly engage said side of the bridge plate, and means journaling the shoe on said one end of the arm, whereby the force imposed on the arm by the spring is transmitted to the bridge plate through the shoe, and the shoe slides along the bridge plate as the bridge plate is raised and lowered. i 

1. Apparatus for counterbalancing a bridge plate hinged to a supporting structure for swinging movement between a substantially vertical position and a substantially horizontal position, comprising: an elongated housing; means securing the housing to the supporting structure on the side of the bridge plate toward which the bridge plate swings in moving toward a horizontal position; an elongated shaft journaled in the housing substantially parallel with the swinging axis of the bridge plate and protruding from at least one end of the housing; an arm having one end thereof adapted to movably engage the bridge plate; mounting means for securing the arm on the shaft with the arm extending substantially radially from the shaft at any one of a plurality of different circumferential positions with respect to a shaft; a helical spring telescoped around the shaft in the housing having one end thereof secured to the shaft and the other end thereof anchoreD to the housing for urging the arm toward the bridge plate when wound in torsional tension; and means for turning the shaft and winding the spring, whereby the spring may be placed under a selected torsional tension and then the arm secured to the shaft with said one end thereof in contact with the bridge plate to adjust the counterbalancing force exerted on the bridge plate by the arm.
 2. Apparatus as defined in claim 1 wherein said means for turning the shaft and winding the spring includes wrench flats on the shaft positioned exteriorly of the housing.
 3. Apparatus as defined in claim 2 wherein the shaft protrudes from both ends of the housing, the mounting means is secured on one end of the shaft, and said flats are on the opposite end of the shaft.
 4. Apparatus as defined in claim 3 wherein the opposite ends of the housing have end cover plates secured thereon apertured to receive the shaft, and characterized further to include a lubricant seal on each end cover plate around the shaft to prevent leakage of lubricant from the housing.
 5. Apparatus as defined in claim 1 wherein the shaft has a circumferential flange thereon within and adjacent one end of the housing, a slot in the flange for anchoring the respective end of the spring therein, and characterized further to include a drive plate secured in the opposite end portion of the housing around and out of engagement with the shaft having a slot therein for receiving and anchoring the opposite end of the spring.
 6. Apparatus as defined in claim 5 wherein the inner diameter of the spring is larger than the outer diameter of the shaft, and characterized further to include circumferentially spaced guides on the shaft adjacent the flange and the drive plate for facilitating the centering of the spring around the shaft during assembly of the apparatus.
 7. Apparatus as defined in claim 1 wherein an end portion of the shaft protruding from the housing has a plurality of circumferentially spaced splines thereon and the mounting means has a bore therethrough and a plurality of circumferentially spaced mating splines in the bore, whereby the mounting means may be secured on the shaft at a plurality of different circumferential positions with respect to the shaft.
 8. Apparatus as defined in claim 7 wherein that portion of the arm associated with the mounting means has a polygonal cross section, the mounting means has a mating bore therethrough extending at a right angle to the first mentioned bore slidingly receiving the arm, and setscrews in the mounting means positioned to engage the arm, whereby the effective length of the arm may be adjusted.
 9. Apparatus as defined in claim 7 wherein the splines on the shaft are tapered inwardly toward the respective end of the shaft, the splines in the mounting means are similarly tapered, and the end of the shaft adjacent the shaft splines is threaded to receive a nut for wedging the mounting means on the shaft.
 10. Apparatus as defined in claim 1 characterized further to include a shoe adapted to slidingly engage said side of the bridge plate, and means journaling the shoe on said one end of the arm, whereby the force imposed on the arm by the spring is transmitted to the bridge plate through the shoe, and the shoe slides along the bridge plate as the bridge plate is raised and lowered. 